fuel problem with a 1972 dodge dart

[mchlwany]

I have a 72 Dart Swinger with a 318, 2bbl and a A-727 Torqueflite transmission. My family has 3 Mopars my Dart a 65 Coronet 500 (hemispherical heads 318 , 2bbl) and a 67 Plymouth Fury 2 (poly 318 , 2bbl) . Im getting 7.8MPG and i cant understand why the other 318's get way better fuel economy. Can anyone explain why? Im a bit new to owning a Mopar so any help is greatly appreciated. Thanks in advance

 

[70aarcuda]

67 Plymouth is no lite weight...

what state of tune is the engine in?

how many miles on it?

your driving habits?

those 318 are Poly not hemi.....

 

[mchlwany]

what do you mean by state of tune? i just had the carb rebuilt about 2 months ago it has 81670 miles. im 16 so as far as driving habits go i dont race it and im not agressive with the engine it has no clutch on the fan if that helps and the ac buttons dont work so the ac is never ran. oh thanks for correcting me im new too this so its good to know what i need to relearn

 

[67Dart273]

Over 80K miles is "getting there" if the engine has never had any work. Could be that the timing chain/ sprockets is worn badly and maybe even off a tooth by now

Minimum I'd do a compression check, and check the tuneup to be sure the timing is OK, and that the mechanical and vacuum advance are not failed

With over 80K, it could have some bad valves. Check the heat riser butterfly that it's not stuck, and that the choke is not stuck shut.

How about your driving? Even if you drive carefully, if most of your driving is slow around town stuff (to school, etc) it won't get very good mileage, and...

how about short trips? Let's say your ride to school/ work is short, it has little time to warm up

Here's a complete 72 shop manual that was posted not long ago, you can download for free.

http://www.forabodiesonly.com/mopar/showthread.php?t=132309&highlight=manual,+download

 

[mchlwany]

thanks for the link. when my dad got the car from his work in 02 he decarbond the engine. is it posible that i need to decarbon it? i dont drive to school i dont have my permit just yet but its been driven a good amount every month. what would some of the signs of the vac. advance failing? the past owner said it sat for around 7 years. i usally dont warm it up too long when i drive it somewhere usally i give it 3 to 5 mins then kick it down and go. all the driving around town is speed limit but how can my mom and dads car get better with the same engines? ill have to check all those parts you metion and get back to you on those.

 

[mchlwany]

Over 80K miles is "getting there" if the engine has never had any work.

well my dad decarbond the engine thats all i know he did to the engine in 02. The spark plugs have been replaced and new belts if thats considered work to the engine. The guy that rebuilt my carb also had a 72 swinger with a 318 long ago when he drove mine around he siad it may have a shift kit and a mild cam. Would it hurt to replace the advance anyways?